SF-3913 Pause sending of ops to ShareDB if offline

src/SIL.XForge.Scripture/ClientApp/src/app/shared/text/text.component.ts

@@ -154,6 +154,7 @@ export class TextComponent implements AfterViewInit, OnDestroy {
   private activePresenceSubscription?: Subscription;
   private onDeleteSub?: Subscription;
   private localSystemChangesSub?: Subscription;
+  private onlineSubscription?: Subscription;
   private readonly DEFAULT_MODULES: any = {
     toolbar: false,
     keyboard: {
@@ -1213,6 +1214,23 @@ export class TextComponent implements AfterViewInit, OnDestroy {
     // But if getText does not return, then we are showing a good message.
     this.loadingState = 'offline-or-loading';
     const textDoc = await this.projectService.getText(this._id);
+
+    // When the user appears offline, ensure that the user's ops are not sent to ShareDB by pausing sending.
+    // This will prevent the ViewModel's fixSegment offline-specific logic causing issues with a flaky connection.
+    this.onlineSubscription?.unsubscribe();
+    this.onlineSubscription = this.onlineStatusService.onlineStatus$
+      .pipe(quietTakeUntilDestroyed(this.destroyRef))
+      .subscribe(isOnline => {
+        if (isOnline) {
+          textDoc.adapter.resume();
+        } else {
+          textDoc.adapter.pause();
+        }
+      });
+    if (!this.onlineStatusService.isOnline) {
+      textDoc.adapter.pause();
+    }
+
     this.loadingState = 'loading';
     this.viewModel.bind(this._id, textDoc, this.subscribeToUpdates);
     if (this.viewModel.isEmpty) this.loadingState = 'empty-viewModel';

src/SIL.XForge.Scripture/ClientApp/src/typings/sharedb.d.ts

@@ -123,6 +123,8 @@ declare module 'sharedb/lib/client' {
     whenNothingPending(callback: Callback): void;
     hasWritePending(): boolean;
     flush(): void;
+    pause(): void;
+    resume(): void;
     previousSnapshot(): Snapshot;
   }
 

src/SIL.XForge.Scripture/ClientApp/src/xforge-common/memory-realtime-remote-store.ts

@@ -91,6 +91,7 @@ export class MemoryRealtimeDocAdapter implements RealtimeDocAdapter {
     on: (_event: string, _handler: Function) => {},
     off: (_event: string, _handler: Function) => {}
   } as Presence;
+  paused: boolean = false;
   submitSource: boolean = false;
   subscribed: boolean = false;
   version: number = -1;
@@ -127,6 +128,14 @@ export class MemoryRealtimeDocAdapter implements RealtimeDocAdapter {
     return Promise.resolve();
   }
 
+  pause(): void {
+    this.paused = true;
+  }
+
+  resume(): void {
+    this.paused = false;
+  }
+
   subscribe(): Promise<void> {
     this.subscribed = true;
     return Promise.resolve();

src/SIL.XForge.Scripture/ClientApp/src/xforge-common/realtime-remote-store.ts

@@ -50,6 +50,8 @@ export interface RealtimeDocAdapter {
   exists(): Promise<boolean>;
   delete(): Promise<void>;
   updatePendingOps(ops: any[]): void;
+  pause(): void;
+  resume(): void;
   previousSnapshot(): Promise<Snapshot>;
 
   destroy(): Promise<void>;

src/SIL.XForge.Scripture/ClientApp/src/xforge-common/sharedb-realtime-remote-store.ts

@@ -420,6 +420,14 @@ export class SharedbRealtimeDocAdapter implements RealtimeDocAdapter {
     this.doc.flush();
   }
 
+  pause(): void {
+    this.doc.pause();
+  }
+
+  resume(): void {
+    this.doc.resume();
+  }
+
   previousSnapshot(): Promise<DataSnapshot> {
     return new Promise((resolve, reject) => {
       this.doc.connection.fetchSnapshot(